1. Field of the Invention
The present invention relates to shifter circuitry for use in a data processing system. In particular, the present invention relates to a structure and method for independently shifting a plurality of bytes in a data processing system.
2. Description of the Prior Art
Real time digital signal processing in applications such as video signal processing requires high computational rates. To help achieve these rates, shifter circuitry has been used to shift a plurality of data bytes. Prior art shifters typically utilize barrel shifter circuitry to allow a plurality of bytes to be shifted by a fixed number of bits. That is, all bytes are shifted in the same direction by the same number of bits.
In addition to byte shifting, certain data processing operations require byte reordering. This reordering is typically performed by separate multiplexer circuitry. As a result of the separate byte shifting and reordering circuitry, the speed of prior art video signal processing has been limited. In addition, the prior art byte shifting and reordering circuitry consumes a relatively large area on the video signal processing chip.
It would therefore be desirable to have a shifter circuit which exhibits a reduced layout area and allows data bytes to be independently shifted and reordered on the same clock cycle.